Abstract:
Vein type carbon-rich graphite deposits found in Sri Lanka occur in metamorphic rocks as narrow steeply dipping veins. These graphite deposits are mined by underground mining, mostly by applying the overhand cutandfill method. Graphite mining at Bogala mines, Sri Lanka, is a unique example of narrow vein mining where the overhand cut-and-fill method is applied as the most suitable mode of mining for years. This method has been widely used in many countries for vein type or narrow orebody mineral extraction. Generally, in this method, the orebody (vein) is extracted by a series of successive stopes within a particular block of orebody.
Although the overhand cut-and-fill method has been traditionally successful, ensuring high recovery, less dilution and good safety, only limited studies have been carried out with an engineering input to evaluate this method. In Bogala mines, the adoption of the overhand cut-and-fill mining method is influenced by the steeply dipping vein environment with rock intercalations and high water inflows with less competent country rock.
This paper looks at the suitability of the present overhand cut-and-fill method practiced in extracting narrow graphite veins of Bogala graphite mines in Sri Lanka and will outline the pros and cons of the method.